After summoning the Watcher, the Fantastic Four hear the tale of a mighty race called the Eternals and how they grew from an advanced society to one of conquerors. But the Eternals met their match when they started a war with another ancient race from the planet Gigantus.

The war cost both civilizations their home worlds and their existence, but the Eternals bound up their entire race memory in the body of one man, the Over-Mind.

With the background, the FF set out to take on the Over-Mind but when Reed turns on the rest of the team they figure he has already been possessed by the Over-Mind.